Israeli soldiers take part in an operation to locate three Israeli teens near the West Bank City of Hebron June 21, 2014.

Israel's army said it detained another 37 Palestinians overnight as it searched for three missing teenagers and extended a crackdown on the Hamas Islamist group it accuses of kidnapping them.

There were no reports of clashes between the soldiers and Palestinians in the raids in the Israeli-occupied West Bank, where the military says it has detained 361 people since the Israeli students went missing on June 12.

The crisis has stepped up tensions in the West Bank which, along with east Jerusalem and the Hamas-controlled Gaza Strip, Palestinians want as part of a future state.

An Israeli military spokeswoman said the latest operations took place in Jenin, a militant stronghold, and in the Hebron area, close to where the three disappeared while hitchhiking.

Palestinian officials said Israeli soldiers also entered Bethlehem and Nablus.

Hamas has neither confirmed nor denied responsibility for the disappearance of the students - Gil-Ad Shaer, U.S.-Israeli national Naftali Fraenkel, both aged 16, and Eyal Yifrah, 19.

Hospital officials in the West Bank said four Palestinians have been killed during clashes with Israeli forces since the search for the teenagers began.

The kidnapping and subsequent arrests have also put pressure on a unity pact between Hamas and Palestinian President Mahmoud Abbas. Israel has urged the Western-backed leader to scrap the agreement.

Abbas has condemned the kidnappings and his security forces have been helping in the search - cooperation that has stirred anger among Palestinians.

But he has also called the Israeli sweeps "collective punishment" and his Palestinian Authority has sought to convene the U.N. Security Council to try to end the incursions.

The Palestinian Liberation Organization, the Palestinians' main ruling body, said in a statement that Israel had "tightened and sometimes closed checkpoints", disrupting travel, and had barred any entry or exit from Hebron in the past 10 days.

Hamas has called for Israel's destruction, although various officials have at times indicated a willingness to negotiate a long-term ceasefire.

The United States and the European Union classify Hamas as a "terrorist" group and shun contact with it, noting its refusal to recognize Israel, renounce violence or accept existing Israeli-Palestinian interim peace agreements.